rock quartet Sigur Rós are trying to figure out how, in the last few months, they've gone from pleasant obscurity to being one of the most talked-about bands on the planet.

The Reykjavik group's swooning, orchestral art pop disc Agaetus Byrjun was released with little fanfare in 1999, but has suddenly set off a surreal bidding war amongst every American major label, despite the fact that the group plays epic, eight-minute songs that crawl along and are sung in Icelandic.

The album topped North Atlantic pop charts for months and made Sigur Rós superstars in Iceland, which is actually a bigger deal than it might sound, while support tours for Radiohead and godspeed you black emperor! spread the word further.

It's hardly the stuff of pop-star dreams, and considering that elastic-voiced singer Jonsi Birgisson has no plans to sing in English, and the band aren't writing any snappy new pop tunes -- "Our songs are getting longer now," they joke -- it's difficult to imagine what MCA, who just signed Sigur Rós, sees in the group.

"I honestly don't know," bassist Georg Holm laughs from a seagull-infested beach in his new hometown of Brighton. "Everything happens to us in small blasts. Things go vroom, and then they stop for a year, and then they go vroom again. Right now, we are in the vroom phase.

"When we released the record back home, we hoped to sell 1,000, which is quite good for Iceland. Now we've sold 15,000 there, which is outrageous. It's gone triple-gold."

Agaetus Byrjun is the kind of record that can change the mood of the room it's played in, leaving critics tongue-tied trying to describe the sombre swell of a track like Staralfur.

"Someone once told us that it was the most moving thing they'd heard since ABBA," Holm giggles. "I thought that was very funny. Then with all the people asking for my autograph, I started to feel like I was in ABBA.

"It's really important for us to get a reaction, especially during concerts. If people don't feel anything, it gets a bit like brushing your teeth. You're just playing the songs, rather than really playing the songs.

"We try to play in rooms like theatres and churches that have an atmosphere. As soon as people walk in, they get into the mood of the place, as opposed to an arena where the first thing that comes to mind is that you went here, got drunk, saw some rock band and went home."

When Sigur Rós' music is described, it's usually in relationship to Iceland's glacial environment. An even more influential factor in the group's sound is the bustling Reykjavik music scene, a tight-knit community that, according to Holm, fosters experimentation and individualism and feverishly supports oddball projects like the Appart Organ Quartet.

"People in Iceland aren't afraid of making mistakes," he explains. "It's a small country and people have no real expectations, so anything's possible.

"For us, it's been great because we can lock ourselves up. You can close the door in Iceland and no one will come knocking for a year if you want. You can stay somewhere and evolve, which is what we did."

While Sigur Rós are desperate to retreat to their new studio -- an old swimming pool built in 1937 -- to begin work on Agaetus Byrjyn's overdue follow-up, the question is, how will the band's sound progress?

The handful of new songs available online continue the mood, but with Holm living in England and much of the band's growth happening on tour beyond Iceland, outside influences are bound to creep in.

"I don't think they will, actually," Holm counters. "Because we were born and brought up in Iceland, Iceland has affected us forever. Wherever we go from now on won't affect us. It's very hard to tell, but the songs we're working on now could never have come out of London or Barcelona.

"The new record's going to be a little more live and a little less produced, maybe a little more raw. It's still a mystery, though, even to us."